Celestial Objects for Common TelescopesLongmans, Green, 1873 - 343 páginas |
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Página 2
... achromatic by the younger Tulley , 5 feet in focal length , * with an aperture of 37 inches , and of fair defining power ; smaller instruments of course will do less , especially with faint objects , but are often very perfect and ...
... achromatic by the younger Tulley , 5 feet in focal length , * with an aperture of 37 inches , and of fair defining power ; smaller instruments of course will do less , especially with faint objects , but are often very perfect and ...
Página 4
... achromatic , notwithstanding the derivation of its name , will shew colour under high powers where there is a great contrast of light and darkness . This ' outstanding ' or uncorrected colour results from the want of a perfect balance ...
... achromatic , notwithstanding the derivation of its name , will shew colour under high powers where there is a great contrast of light and darkness . This ' outstanding ' or uncorrected colour results from the want of a perfect balance ...
Página 6
... achromatic . The interposition of a combination called a Barlow lens raises the power with little loss of light ; and as one will suit all the eye - pieces , it doubles the set at a small expense . The silvered specula mounted by ...
... achromatic . The interposition of a combination called a Barlow lens raises the power with little loss of light ; and as one will suit all the eye - pieces , it doubles the set at a small expense . The silvered specula mounted by ...
Página 20
... achromatic . With large apertures , a plane sur- face of unsilvered glass placed diagonally , as originally sug- gested by Herschel II . , so as to reflect only a small fraction of the light and heat , is found of eminent service . Merz ...
... achromatic . With large apertures , a plane sur- face of unsilvered glass placed diagonally , as originally sug- gested by Herschel II . , so as to reflect only a small fraction of the light and heat , is found of eminent service . Merz ...
Página 22
... achromatic is employed , it is an excellent plan to shade the face in the one case , or the screen in the other , by a large piece of pasteboard with a hole in it , through which the tube passes . All being arranged , we shall find four ...
... achromatic is employed , it is an excellent plan to shade the face in the one case , or the screen in the other , by a large piece of pasteboard with a hole in it , through which the tube passes . All being arranged , we shall find four ...
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Términos y frases comunes
achr achromatic aperture Aquil astronomers atmosphere beautiful Binary bluish Boöt bright brighter brilliant Buffham Cassini centre Ceph Clusters colour comet constellation craters curious dark Dawes deep diameter disc Double Stars Drac dusky Earth eye-piece faint field flushed white globe greenish grey Herc Herschel Huggins interior Jupiter larger Lassell libration light lilac limb luminous lunar minute stars Moon motion naked eye nearly nebulæ noticed nucleus object object-glass observers orange pair pale blue pale white pale yellow photosphere Pisc planet proper motion Red Star reflector region remarkable Right Ascension ring ruddy satellites Schm Schr Schröter Schwabe Secchi seen shadow shew side silvery white smaller smalt solar sometimes spec spots streaks surface Taur telescope topaz Triple Virg visible xIxh xvih XVIII yellowish
Pasajes populares
Página 345 - A NEW STAR ATLAS, for the Library, the School, and the Observatory, in Twelve Circular Maps (with Two Index Plates). Intended as a Companion to ' Webb's Celestial Objects for Common Telescopes.
Página 46 - Fairest of stars, last in the train of night, If better thou belong not to the dawn, Sure pledge of day, that crown'st the smiling morn With thy bright circlet, praise Him in thy sphere, While day arises, that sweet hour of prime.
Página 182 - Lift up your eyes on high, and behold who hath created these things, that bringeth out their host by number; he calleth them all by names by the greatness of his might, for that he is strong in power; not one faileth.
Página 345 - Why didn't somebody teach me the constellations, too, and make me at home in the starry heavens which are always overhead, and which I don't half know to this day?
Página 30 - I have said, he spent to satisfy himself; six more years to satisfy, and still thirteen more to convince, mankind. For thirty years never has the Sun exhibited his disc above the horizon of Dessau without being confronted by Schwabe's imperturbable telescope, and that appears to have happened, on an average, about 300 days a year.
Página 65 - Webb makes the following remarks on the rills:—"These most singular furrows pass chiefly through levels, intersect craters (proving a more recent date), reappear beyond obstructing mountains, as though carried through by a tunnel, and commence and terminate with little reference to any conspicuous feature of the neighbourhood.